IgAN is defined as an autoimmune disease characterized by the deposition of immunocomplexes containing Gd-IgA1 antibodies in the glomerular mesangium with an incidence of 2.5/100000 per year. The main pathomorphological changes of IgAN, which are part of the Oxford classification from 2016, are: mesangial, endocapillary and extracapillary proliferation, segmental glomerulosclerosis and tubular atrophy/interstitial fibrosis. The study included patients whose eGFR value at the time of biopsy was >15 ml/min/1.73 m2. Patients with secondary IgAN were excluded. The observation period was 3 years or less if ESRD development, dialysis or death occurred. The previous three criteria also formed the end point of the study. This study found that the group with the development of ESRD had a lower value of eGFR at the time of biopsy compared to those without the development of the same (p=0.003). For the group with T1+2 criteria, a higher frequency of ESRD development was proven compared to the group with T0 criteria (p=0.025). ROC curve analysis, for eGFR values at the time of biopsy, resultated with an AUC of 0.844 (95% CI 0.657-0.952) (p<0.001) with the breakdown value of ≤44 ml/min/1.73m². Univariate analysis by logistic regression, with a breakdown value eGFR of <44 ml/min/1.73m², resultated with an OR of 16.33 (95% CI 1.632-163.446) (p=0.018). By the same analysis, with T1+2 criteria, OR was obtained in the amount of 10.50 (95% CI 1.076-102.483) (p=0.043). Multivariate analysis by logistic regression, with previous two parameters, did not determine the statistical significance of OR (p>0.05). Patients are more likely to develop ESRD if the eGFR value, at the time of biopsy, is <44 ml/min/1.73m2 and/or the pathohistologically confirmed T1+2 criteria.